Palaeoenvironmental implications of palygorskite clays in Eocene deep-water sediments from the western Central Atlantic
Thomas Pletsch, 2001. "Palaeoenvironmental implications of palygorskite clays in Eocene deep-water sediments from the western Central Atlantic", Western North Atlantic Palaeogene and Cretaceous Palaeoceanography, Dick Kroon, R. D. Norris, A. Klaus
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Clay mineral analyses were performed on Eocene sediments from drill sites in the western Central Atlantic. The investigated sites cover the full range of early Palaeogene deep waters above and below the calcite compensation depth (CCD), but otherwise represent different depositional and hydrographic regimes. Palygorskite clays with authigenic microstructures were discovered in Lower Eocene hemipelagic sediments from the distal end of the Blake Nose depth transect and in pelagic clays of the same age from the distal Nares Abyssal Plain, where terrigenous input was reduced. Palygorskite clays were not detected in coeval sediments from a distal near-CCD setting on Bermuda Rise that received major terrigenous input. The distribution of palygorskite clays at these sites, the microstructures of the constituent minerals, their absence from contemporaneous deposits on the American margin, and the position of the northerly sites outside the range of a potential African aeolian supply strongly suggest an authigenic origin of these clays at the early Eocene sea floor. Palygorskite clays are widely distributed in lower Eocene sediments from about 50° N to 50° S palaeolatitude. The most widespread distributions and peak abundances in Atlantic oceanic sediments are reported from shelf to deep-water sites of the palaeo-tropical and -subtropical belt and correlate with the Early Eocene period of extreme warmth. Marine authigenic palygorskite clay may provide an indication of the localities and the time periods that were characterized by high bottom-water temperatures, by elevated alkalinity, silica and magnesium concentrations, and by reduced sediment accumulation rates.